title: Heavy chain ferritin siRNA delivered by cationic liposomes increases sensitivity of cancer cells to chemotherapeutic agents.
abstract: Approximately half of all gliomas are resistant to chemotherapy, and new therapeutic strategies are urgently needed to treat this cancer. We hypothesized that disrupting iron homeostasis in glioma cells could block tumor growth, based on an acute requirement for high levels of iron to meet energy requirements associated with their rapid growth. Ferritin is best known as an intracellular iron storage protein, but it also localizes to tumor cell nuclei where it seems to protect DNA from oxidative damage and to promote transcription. In this study, we hypothesize that silencing the H-ferritin (heavy chain ferritin) gene could increase tumor sensitivity to chemotoxins. To test this hypothesis, H-ferritin siRNA was delivered to several human cancer cell lines by using cationic liposomes (C-liposome). H-ferritin siRNA decreased protein expression by 80% within 48 hours, and this decrease was associated with more than 50% decrease in the LD(50) for DNA-alkylating agent carmustine (BCNU), which is commonly used to treat glioma in clinic. In a subcutaneous mouse model of human glioma, intratumoral injections of liposomes containing H-ferritin siRNA reduced the effective dose of BCNU needed for tumor suppression by more than 50%. A plasmid supercoil relaxation assay showed that H-ferritin specifically and directly protected DNA from BCNU treatment. H-ferritin siRNA additionally seemed to increase apoptosis in glioma cells in vitro upon H-ferritin knockdown. Overall, our results illustrate how silencing H-ferritin can effectively sensitize tumors to chemotherapy and also show the ability of C-liposomes to serve as a novel in vivo delivery tool for siRNAs.
authors.affiliation: Department of Neurosurgery, Penn State Cancer Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, USA.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Liu
authors.forename: A B
authors.initials: AB
authors.lastname: Madhankumar
authors.forename: Becky
authors.initials: B
authors.lastname: Slagle-Webb
authors.forename: Jonas M
authors.initials: JM
authors.lastname: Sheehan
authors.forename: Nodar
authors.initials: N
authors.lastname: Surguladze
authors.forename: James R
authors.initials: JR
authors.lastname: Connor
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D001052:Apoferritins / Q000737:chemistry / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D002330:Carmustine / Q000627:therapeutic use; D053148:Caspase 3 / Q000378:metabolism; D002412:Cations / Q000737:chemistry; D045744:Cell Line, Tumor; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005260:Female; D005910:Glioma / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008081:Liposomes / Q000737:chemistry; D051379:Mice; D008819:Mice, Nude; D009690:Nucleic Acid Conformation / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics*; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D018906:Antineoplastic Agents, Alkylating; D002412:Cations; D004273:DNA, Neoplasm; D004278:DNA, Superhelical; D008081:Liposomes; D034741:RNA, Small Interfering; D001052:Apoferritins; D053148:Caspase 3; D002330:Carmustine